/**
* 
* @param {*} lon 经度
* @param {*} lat 纬度
* @param {*} angle 角度 (0~360度)
* @param {*} distance 距离 (米)
*
*/
export default  function get_another_point(lon, lat, angle, distance) {
    // WGS84坐标系
    var a = 6378137 // 赤道半径
    var b = 6356752.3142 // 短半径
    var f = 1 / 298.257223563 // 扁率
  
    var alpha1 = angle * (Math.PI / 180)
    var sinAlpha1 = Math.sin(alpha1)
    var cosAlpha1 = Math.cos(alpha1)
    var tanU1 = (1 - f) * Math.tan(lat * (Math.PI / 180))
    var cosU1 = 1 / Math.sqrt(1 + tanU1 * tanU1),
      sinU1 = tanU1 * cosU1
    var sigma1 = Math.atan2(tanU1, cosAlpha1)
    var sinAlpha = cosU1 * sinAlpha1
    var cosSqAlpha = 1 - sinAlpha * sinAlpha
    var uSq = (cosSqAlpha * (a * a - b * b)) / (b * b)
    var A = 1 + (uSq / 16384) * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)))
    var B = (uSq / 1024) * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)))
    var sigma = distance / (b * A),
      sigmaP = 2 * Math.PI
    while (Math.abs(sigma - sigmaP) > 1e-12) {
      var cos2SigmaM = Math.cos(2 * sigma1 + sigma)
      var sinSigma = Math.sin(sigma)
      var cosSigma = Math.cos(sigma)
      var deltaSigma = B * sinSigma * (cos2SigmaM + (B / 4) * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) - (B / 6) * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)))
      sigmaP = sigma
      sigma = distance / (b * A) + deltaSigma
    }
  
    var tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1
    var lat2 = Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1, (1 - f) * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp))
    var lambda = Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1)
    var C = (f / 16) * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha))
    var L = lambda - (1 - C) * f * sinAlpha * (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)))
  
    // var revAz = Math.atan2(sinAlpha, -tmp); // final bearing
  
    return { lon: Number(lon) + L * (180 / Math.PI), lat: lat2 * (180 / Math.PI), alt: 80000 }
  }
  